Precise Synthesis and Broadband Photoresponse of Two-Dimensional Intrinsic Vacancy Semiconductor

Two-dimensional (2D) intrinsic vacancy semiconductors possess great application prospects in optoelectronics fields, originating from abundant intrinsic vacancy structures and exceptional physical properties. Understanding the structure-activity relationship between vacancies and physical/photoelectric properties is significant for building advanced photoelectric devices. However, limited by the increasing instability of 2D structure induced by intrinsic vacancies, the precise synthesis of 2D intrinsic vacancy semiconductors faces great challenges. Here, high-quality 2D intrinsic vacancy semiconductor alpha-Ga2Se3 is synthesized via low-pressure and space-confined physical vapor deposition. The vacancy structures induce an intermediate energy level and a super-bandgap photoluminescence (PL) peak, which are verified by temperature-dependent PL spectra. Furthermore, the vacancy energy level favorably endows 2D alpha-Ga2Se3-based photodetector with a UV-vis-NIR super-bandgap photoresponse, excellent ultraviolet detection ability (photoresponsivity (41.86 A W-1), epitaxial quantum efficiency (1.42 x 10(4)%), and detectivity (6.69 x 10(11) Jones) @365 nm), fast photoresponse (20 ms), and superior photocurrent-light power-fitting factors. In addition, 2D alpha-Ga2Se3-based phototransistor displays p-type transport behavior with a responsivity of 10(5) A W-1@365 nm at a gate voltage of -40 V. This work suggests a bright future of 2D intrinsic vacancy semiconductors in tailoring physical properties and enabling sophisticated device functionality.